Inverse relationship between platelet density and reactivity alterations at coronary angiography

This work investigates relationships between platelet density and reactivit y. 21 individuals subject to coronary angiography were studied. Peak platel et density was analyzed using a newly developed electronic device. The appa ratus measures light transmission through test tubes containing density-sep arated platelets, thus allowing an estimation of the platelet distribution in the gradient. A flow cytometry technique was used for determining platel et reactivity after stimulating with ADP. Platelet counts, mean platelet vo lumes, peak platelet density and platelet reactivity were determined immedi ately before (day 1) and 24 h after cardiac catheterization (day 2). For al l parameters changes during the day of angiography were compared with plate let density alterations. The subjects were divided into two groups accordin g to density changes at angiography. Group 1 individuals showed density alt erations (i.e. day 2 - day 1 value) greater than or equal to -8 x 10(-5) kg /l. In contrast, group 2 subjects either displayed density changes <-8 x 10 -5 kg/l or grossly disturbed platelet density patterns on day 2. Before ang iography both groups had similar platelet counts and volumes. Then platelet reactivity when stimulating with ADP did not differ significantly between the two groups. After angiography, the number of fibrinogen-positive cells when stimulating with ADP rose by 6 +/- 8% for group 2 patients. The corres ponding figure for group 1 was -1 +/- 6%. The difference was significant (p = 0.01). No such relationships were found when comparing density alteratio ns and changes of platelet counts and volumes. We conclude that in this stu dy platelet density alterations at coronary angiography are inversely relat ed to variations of platelet reactivity. Copyright (C) 2001 S. Karger AG, B asel.